In a paper published Tuesday in the journal Sex Roles, Professor of Psychology Terri Fisher surveyed a group of 293 heterosexual male and female college students on their sexual history, as well as on other nonsexual activities relating to gender roles.

What she found was that both men and women appeared to lie about their sexual history, but in different ways.

When students were asked to fill out an anonymous paper survey, male students reported having sex at an earlier age and with more people than the female students.

However, when students were hooked up to a fake polygraph machine, the female students, on average, were more likely to report that they had more partners than the male students.

"It was the exact opposite," Fisher said of the fake lie detector answers. "Women are reporting significantly more partners than the men."

When not attached to the fake lie detector, the male students tended to add one more partner to their sexual history, while the women tended to subtract one.

Fisher, who specializes in the study of sexuality and gender roles, said that the men and women were less likely to alter their answers regarding other gender-related behaviors, such as cooking, petting a kitten, changing a car tire, dressing like the other sex or driving at 90 mph.

In other words, men and women appeared to be less hesitant to admit to activities that might be associated with the opposite sex, as long as they didn't involve sexual behavior. When it came to intercourse, men and women appeared to be intent on answering along stereotypical expectations, Fisher said.

Fisher said the findings should raise flags with researchers who use surveys to study sexuality. "It is possible that people are more motivated to hide sexual behavior that is not in keeping with gender norms than other types of behavior," Fisher wrote.

The average age of the study participants was 18, and the overwhelming majority of them were white.

The study mirrored results of an experiment Fisher conducted in 2003. However, in that study women who were connected to a fake lie detector -- "bogus pipeline," as psychologists call it -- admitted to having, on average, the same number of sexual partners as the men.

It was unclear why, 10 years later, women were now reporting that they had a greater number of partners than men.

"With research like this, it's always difficult to separate out whether the change is in actual behavior or whether the change is in willingness to admit the behavior," Fisher said.

Catasauqua police officer Scott M. Rothrock had already been stabbed once in the chest with a 13-inch butcher knife and was trying to block other stabbing attempts as he lay on his back in a snow bank in east Allentown last month.